The ideal vehicle crash would, of course, be no crash at all. But, assuming there is going to be a crash, it is desirable to maximize possible chances of human survival, collectively utilizing safety systems in the vehicle to allow for the smoothest crash possible.
Surviving a vehicle crash involves minimizing kinetic energy. When a passenger's body is moving at 35 mph, it has a certain amount of kinetic energy. After the crash, when the passenger comes to a complete stop, he has zero kinetic energy. To minimize risk of injury, it is desirable to remove the kinetic energy as slowly and evenly as possible. Some of the safety systems in vehicles help do this.
Ideally, a vehicle has seatbelt pretensioners and force limiters; they both tighten up the seatbelts very soon after the car hits a barrier, but before an airbag deploys. The seatbelt can then absorb some of the passenger's energy as he moves forward towards the airbag. Milliseconds later, the force in the seatbelt holding the passenger back would start to hurt him, so the force limiters kick in now, making sure the force in the seatbelts does not get too high. Next, the airbag deploys and absorbs some more of the passenger's forward motion while protecting the passenger from hitting anything hard.
In this hypothetical crash, the safety systems in the car all worked together to slow the passenger down. If the passenger did not wear a seatbelt, then the first stage of protection is lost and he is more likely to be injured when he collided into the airbag. Many cars have seatbelt pretensioners and force limiters, but there are some even more exciting safety improvements being developed.
Recently, it seems like air bags have become commonplace in most cars. And if they help prevent passengers from hitting hard objects during a collision, they are doing their job. But, there is always room for improvement. Right now (and in the foreseeable future) the emphasis on safety equipment is to make it “smarter.”
The most recent advancement in safety equipment is known as a smart air bag. These air bags can deploy with different speeds and pressures, depending on the weight and seating position of the occupant, and also on the intensity of the crash. Unfortunately, the deployment of an air bag is expensive and, in some cases, can cause serious injury and even death to the driver or passenger.
Until recently, most of the strides made in auto safety were in front and rear impacts, even though 40 percent of all serious injuries from accidents are the result of side impacts, and 30 percent of all accidents are side-impact collisions. Many carmakers have responded to these statistics (and the resulting new standards) by improving doors, door frames and floor and roof sections. But cars that currently offer side air bags represent the new wave of occupant protection. Engineers say that designing effective side air bags is much more difficult than designing front air bags. This is because much of the energy from a front-impact collision is absorbed by the bumper, hood and engine, and it takes almost 30 to 40 milliseconds before it reaches the car's occupant. In a side impact, only a relatively thin door and a few inches separate the occupant from another vehicle. This means that door-mounted side air bags must begin deploying in a mere five or six milliseconds.
In light of the difficulty of designing effective side air bags, the device of the present invention seeks to provide an effective and affordable alternative to air bags.